1. Field
Embodiments described herein relate generally to an X-ray diagnostic apparatus and an X-ray diagnostic method.
2. Description of the Related Art
X-ray diagnostic apparatuses include a biplane type of X-ray diagnostic apparatus which can irradiate X-rays to an object from different directions to obtain three dimensional information in a diagnosis part. The biplane type of X-ray diagnostic apparatus has two sets of X-ray tubes and detectors. Each X-ray tube works as an X-ray source while each detector detects X-ray. The biplane type of X-ray diagnostic apparatus also has high voltage generators dedicated to the respective X-ray tubes.
In recent years, an inverter type of high voltage generator having a high power semiconductor device becomes popular as a high voltage generator for a medical X-ray system. This inverter type of high voltage generator has a characteristic that it is possible to save a space by using a high frequency to make a size and weight of the high voltage generator small and to form a nearly constant tube voltage waveform with either a single-phase power or a three-phase one to obtain a high efficiency.
For example, an X-ray diagnostic apparatus for a diagnosis of circulatory organ is often used for a treatment as well as an examination. For that reason, when an output of X-ray stops while a doctor manipulates a catheter in an operation for example, it becomes difficult to manipulate the catheter, which makes a risk against an object high.
Accordingly, the stable operation of an X-ray diagnostic apparatus is very important and a high reliability is strongly required for an X-ray diagnostic apparatus. For that reason, an X-ray diagnostic apparatus having high voltage generators is offered (refer to the patent document 1: Japanese Publication of Patent Application No. 10-27697). This apparatus can continue to output an X-ray even if an abnormality occurs in one of the high voltage generators each including an inverter.
However, the invention disclosed in the above patent document 1 does not consider following points.
That is, the medical X-ray system shown in the above patent document 1 includes only one set of X-ray tube serving as an X-ray source and detector detecting an X-ray. Therefore, two high voltage generators are provided for one X-ray tube. Application of plural high voltage generators with a biplane type of X-ray diagnostic apparatus, which has two sets of X-ray tubes each serving as an X-ray source and detectors each detecting an X-ray, is not described in the patent document 1.
The biplane type of X-ray diagnostic apparatus has a characteristic that three dimensional information of a diagnosis part can be acquired by exposures of X-rays from different directions as described above. Therefore, it is preferable to adopt a configuration that the first high voltage generator for the first plane (imaging system) can power the second plane (imaging system), in order to exert the characteristic with keeping a stable operation of the apparatus. This configuration makes it possible to continue to use the X-ray diagnostic apparatus as the biplane type safely even if an abnormality occurs in one high voltage generator for one plane (imaging system).
On the other hand, one plane of a biplane type of X-ray diagnostic apparatus may be used preferentially depending on a diagnosis object for example. When the plane which cannot be used due to an abnormality is one which should be used preferentially, it is preferable to operate the plane which should be used preferentially even if the other plane stops or an output from the other plane is limited. Alternatively, providing plural high voltage generators with each plane so as to address an abnormality may make a circuitry of X-ray diagnostic apparatus complex and the apparatus expensive.